1. Field of the Invention
The present invention relates to tool platforms, and particularly relates to tool platforms which include a tool-receiving surface which may be selectively disposed at a given angular orientation and elevation relative to an abrading surface of an abrading apparatus. The present invention more particularly relates to an abrading machine including a tool platform having a tool-receiving surface which may be selectively disposed at a given angular orientation and elevation relative to the abrading machine's abrading surface, and most particularly relates to a two-station abrading machine having an adjustable tool platform which may be selectively disposed at either station, and wherein a pre-selected elevation and angular orientation of the tool-receiving surface relative to the abrading surface may be maintained when the tool platform is moved between stations.
2. Description of the Invention Background
A number of modern tools and machines include portions having engageable edges which must be kept free from surface imperfections such as, for example, burrs, nicks and gouges, so that the tool or machine can function properly. For purposes of the present disclosure, the operation wherein such surface imperfections are removed from an edge will be referred to as "grinding". Such tools which should be maintained free from surface imperfections include, for example, flat head screwdrivers, chisels, gouges, the cutter members of planes, spokeshaves and scrapers, and the knife members of planer machines and jointer machines. The presence of surface imperfections on such tools can mar or gouge the surface of a wooden workpiece, requiring additional sanding operations to obtain an acceptable appearance for the workpiece.
In addition to the removal of surface imperfections, a number of tools and machines include edges which must be kept sharp so that the tool or machine can properly cut or remove wood from a workpiece. For purposes of this disclosure, the operation of providing a tool with a sharpened edge will be referred to as "sharpening". Such tools which must be kept sharpened to operate properly include, for example, all types of knife tools, woodworking chisels and gouges, and the knife blades of planer machines and jointer machines.
The operations of both grinding and sharpening, as well as any other activity where material is removed from a surface of a workpiece, will be referred to herein as "abrading".
Perhaps the most rudimentary means for maintaining an edge free from burrs and nicks and/or to sharpen the edge is to use a stone surface, known as a whetstone, oilstone or a bench stone. Such stones may be composed of natural stone or artificial material, such as silicon carbide or aluminum oxide, and come in a variety of grit sizes. By the repeated stroking of a worn edge on the stone at the proper angle, material is abraded from the edge.
To remove surface imperfections from the edge, or to straighten the edge, a stone having a coarse or medium grit size is typically used. To sharpen the edge, a stone having a relatively fine grit size is employed. To properly sharpen an edge, oftentimes both procedures must be employed so that relatively gross surface imperfections are first removed from the edge using a medium or coarse grit stone, and then the edge may be sharpened using a relatively fine grit stone.
When sharpening an edge by subjecting the edge to one or both of the above abrading steps, a constant angle should be maintained between the tool and the abrading surface so that the edge is not sharpened in a rounded configuration. Maintaining a constant angle when sharpening by hand using a stone is quite difficult, in part because the tool must be stroked across the stone surface while maintaining substantially constant pressure between the edge and the stone.
To hasten the removal of material from an edge to be ground or sharpened, and also to aid in maintaining a proper angle between the tool and the abrading surface, a variety of motor-driven grinding and sharpening devices are available. These devices may be capable of either grinding or sharpening, or may provide both features. Many of these abrading devices employ a wheel of a natural or synthetic abrasive material which is driven to rotate by an electric motor.
On such device is the Model GGM-250W grinding/sharpening machine distributed under the trade name Reliant by Trendlines, Chelsea, Massachusetts, which incorporates an 80 grit grinding wheel which rotates on a horizontally-disposed axis and a water-fed 800 grit sharpening wheel which rotates on a vertically-disposed axis. For the purpose of the following description, an abrasive wheel used for grinding which rotates on a horizontally-disposed axis is referred to as a "vertical grinding wheel", while an abrasive wheel used for sharpening which rotates on a vertically-disposed axis is referred to as "a horizontal sharpening wheel". The Reliant machine includes individual tool rests including flat metal pieces which are fixedly attached adjacent each wheel for resting the tool which is to ground or sharpened. A surface of the flat metal piece acts as a tool-receiving surface for supporting the tool to be abraded. The tool rest adjacent the vertical wheel can be adjusted to move out from or toward the perimeter surface of the wheel. The tool rest adjacent the horizontal sharpening wheel includes a flat metal strip having a tool-receiving surface, the flat metal strip having two ends, each of the ends being pivotally connected to one end of a cylindrical post member by a threaded screw and a nut. Each post member is slidingly received in a substantially vertical orientation by collar shaped portion of the machine's housing.
Each of the post members of the Reliant machine must be raised or lowered by hand within the collar-shaped portions to adjust the flat metal strip to a predetermined elevation above the wheel surface and thereby adjust a tool resting on the tool-receiving surface of the flat metal strip to a predetermined elevation above the wheel surface. To secure the individual post members at a selected elevation, a knob member must be threadedly advanced into the side of each collar portion of the machine's housing until it impinges on a surface of the post members and frictionally retains the post members at a selected depth within the collar.
The tool-receiving surface of the Reliant machine may be adjusted to a predetermined angle relative to the wheel surface by pivoting by hand the flat metal strip relative to the vertically-disposed post members. The flat metal strip may be secured at the predetermined angle by hand-tightening each of the two nut-and-screw arrangements which pivotally connect the flat metal strip to the post members.
From the foregoing description of the Reliant machine, it will be understood that the adjustment of the tool-receiving surface of the machine's tool rest adjacent the horizontal sharpening wheel must be accomplished entirely by hand and requires the hand-tightening of no less than four elements to lock the tool rest at a selected elevation and angle relative to the abrading surface. In addition, because the tool-receiving surface of the Reliant machine is disposed on a flat metal strip is supported at its terminal ends, the strip, and consequently the tool-receiving surface, may bow if the tool is pressed onto it with sufficient force. The bowing of the strip will affect the elevation and angle of the supported tool relative to the abrading surface and may also effect the pressure exerted on the abrading surface by the tool edge being sharpened. Finally, maintaining the identical orientation, i.e., elevation and angle, of the tool edge being sharpened to the abrading surface when the tool is transferred between the vertical grinding wheel and the horizontal sharpening wheel of the Reliant machine would be quite difficult because each wheel includes an individual, separately adjustable tool rest.
American Machine & Tool Co, Inc. ("AMT"), Royersford, Pa. and Woodworker's Supply, Albequerque, N. Mex., distribute grinding/sharpening machines which have substantially the same design as the Reliant machine. Adjacent to both the AMT and Woodtek machine's vertical and horizontal wheels are disposed individual tool rests having designs and means for adjustment substantially identical to that of the Reliant machine described above. Accordingly, those machines suffer from the same disadvantages as the Reliant machine.
In addition to the above devices, Makita Electric Works, Ltd., Aichi, Japan, distributes a Model 9820-2 sharpening machine which includes a single sharpening station having a 1000 grit, water-fed, horizontal sharpening wheel. Disposed adjacent the wheel is a tool rest including a support rail having a tool-receiving surface for supporting a tool for sharpening. The support rail is pivotally mounted on one end of two post members by two pin members, the other end of each post member including screw threads thereon and being slidingly received by apertures in the machine's housing.
The depth of the post members within the apertures of the Makita machine, and the consequent elevation of the tool-receiving surface above the wheel surface, is selectively adjusted by threadedly advancing by hand an individual nut member along the threaded second end of each post member; the nut members rest on the aperture's opening and cause the post member to advance into or out of the aperture when rotated. When the post members have been brought to a selected elevation, they may be locked at that elevation by hand tightening two knob members which are threadedly disposed through the machine's housing and which impinge on the post members within the housing when the knob members are sufficiently threadedly advanced into the housing. To adjust the angle of the tool-receiving surface relative to the wheel surface, the first end of one post member threadedly receives a knob member with a threaded end that passes through and may be advanced or retracted through the post member. The threaded end of the knob member protrudes from the post member and impinges in a lower surface of the support rail such that the advancement or retraction of the threaded end through the post member correspondingly pivots the support member toward or away from the wheel surface.
The Makita machine suffers from each of the disadvantages referred to with regard to the Reliant, AMT and Woodtek machines. In addition, the Makita machine does not incorporate a separate grinding wheel and either the grinding operation precedent to sharpening the edge must to accomplished using another machine or the 1000 grit wheel of the Makita machine must be replaced with a relatively coarse grit wheel.
Considering the above-described disadvantages of grinding and/or sharpening machines including tool rests, there exists a need for a new tool platform for supporting a tool adjacent the abrading surface of a grinding or sharpening machine, which tool platform includes easily adjustable means for selecting a given orientation for the tool-receiving surface of the tool rest relative to the abrading surface and for locking the tool-receiving surface in the selected orientation. A need also exists for an abrading machine including an easily adjustable tool platform, and for an abrading apparatus having two or more abrading stations and which also includes a tool platform having means for maintaining an orientation of the tool platform's tool-receiving surface relative to the abrading surface at multiple abrading station.